Experimental study on shear strength characteristics of sulfate saline soil in Ningxia region under long-term freeze-thaw cycles

2019 ◽  
Vol 160 ◽  
pp. 48-57 ◽  
Author(s):  
Weibing Zhang ◽  
Junze Ma ◽  
Lian Tang
Keyword(s):  
Experimental Study ◽  
Shear Strength ◽  
Saline Soil ◽  
Strength Characteristics ◽  
Freeze Thaw

scholarly journals The undrained shear strength characteristics of silty sand: an experimental study of the effect of fines

2011 ◽  
Vol 64 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Mostefa Belkhatir ◽  
Hanifi Missoum ◽  
Ahmed Arab ◽  
Noureddine Della ◽  
Tom Schanz
Keyword(s):  
Experimental Study ◽  
Shear Strength ◽  
Undrained Shear Strength ◽  
Silty Sand ◽  
Strength Characteristics ◽  
Undrained Shear

Experimental study of residual strength and the index of shear strength characteristics of clay soil

2018 ◽  
Vol 233 ◽  
pp. 183-190 ◽  
Author(s):  
Chengshun Xu ◽  
Xin Wang ◽  
Xinyue Lu ◽  
Fuchu Dai ◽  
Shuang Jiao
Keyword(s):  
Experimental Study ◽  
Shear Strength ◽  
Residual Strength ◽  
Clay Soil ◽  
Strength Characteristics

scholarly journals Relationship between the Shear Strength and Microscopic Pore Parameters of Saline Soil with Different Freeze-Thaw Cycles and Salinities

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1709
Author(s):  
Jiaqi Wang ◽  
Qing Wang ◽  
Sen Lin ◽  
Yan Han ◽  
Shukai Cheng ◽  
...  
Keyword(s):  
Shear Strength ◽  
Pore Structure ◽  
Pore Diameter ◽  
Saline Soil ◽  
Soil Samples ◽  
Average Pore Diameter ◽  
Failure Strength ◽  
Average Pore ◽  
Freeze Thaw ◽  
The Relationship

Saline soil is a widely distributed special soil with poor engineering properties. In seasonally frozen regions, the poor properties of saline soil will cause many types of engineering damage such as road boiling, melt sinking, and subgrade instability. These engineering failures are closely related to the shear strength of saline soil. However, there are relatively few studies on saline soil in cold regions. The strength of the soil is always determined by its microstructure; therefore, the study aims to investigate the relationship between the shear strength and microscopic pore structure of saline soil with different freeze–thaw cycles and salinities. The shear strength characteristics of saline soil with different salinities subjected to different freeze–thaw cycles were obtained by triaxial tests. In addition, the microstructure of the soil samples was investigated by scanning electron microscopy (SEM) tests, and the microscopic pore parameters of the soil samples, including porosity (N), average pore diameter (D¯), average shape coefficient (K), surface fluctuation fractal dimension (F), and orienting probability entropy (Hm), were obtained by image processing software quantitatively. Based on the experimental results, the influence of freeze–thaw cycles and salinity on the shear strength characteristics and microstructure of the soil samples were analyzed. Besides that, in order to effectively eliminate the collinearity between independent variables and obtain a stable and reasonable regression model, principal component regression (PCR) analysis was adopted to establish the relationship between the microscopic pore parameters and the failure strength of the soil samples. The fitting results demonstrated that the failure strength of saline soil is mainly related to the size and direction of the pores in the soil, and it has little correlation with pore shape. The failure strength of the soil was negatively correlated with the average pore diameter (D¯) and porosity (N), and it was positively correlated with the orienting probability entropy of the pores (Hm). This study may provide a quantitative basis for explaining the variation mechanism of the mechanical properties of saline soil from a microscopic perspective and provide references for the symmetry between the changes of the macroscopic properties and microscopic pore structure of the saline soil in cold regions.

scholarly journals Improvement of the Salinized Soil Properties of Fly Ash by Freeze-Thaw Cycles: An Impact Test Study

2021 ◽  
Vol 13 (5) ◽  
pp. 2908
Author(s):  
Zhuo Cheng ◽  
Gaohang Cui ◽  
Zheng Yang ◽  
Haohang Gang ◽  
Zening Gao ◽  
...  
Keyword(s):  
Shear Strength ◽  
Fly Ash ◽  
Internal Friction ◽  
Unconfined Compressive Strength ◽  
Saline Soil ◽  
Friction Angle ◽  
Ash Content ◽  
Internal Friction Angle ◽  
Freeze Thaw ◽  
Salinized Soil

To explore the mechanism of the microstructural change in salinized soil under freeze-thaw cycles and the strength characteristics of subgrade salinized soil improved by fly ash, an unconfined compressive test, a triaxial shear test, and a scanning electron microscopy test were carried out using salinized soil samples with different fly ash contents along the Suihua to Daqing expressway in China. The results showed that after several freeze-thaw cycles, the unconfined compressive strength, triaxial shear strength, cohesion, and internal friction angle of saline soil showed a decreasing trend. With an increase in the fly ash content, the internal friction angle, cohesion, unconfined compressive strength, and shear strength of the improved saline soil first increased and then decreased. When the fly ash content was 15%, the mechanical indexes, such as cohesion and the internal friction angle, reached the maximum value. Microscopic test results showed that the freeze-thaw cycle will lead to an increase in the proportion of pores and cracks, an increase in the average pore size, and a loosening of the soil structure. The addition of fly ash can fill the soil pores, improve the microstructure of the soil, increase the cohesive force of the soil particles, and improve the overall strength of the soil. Fly ash (15%) can be added to subgrade soil in the process of subgrade construction in the Suihua-Daqing expressway area to improve the shear strength and the resistance to freezing and thawing cycles. These research results are conducive to promoting the comprehensive utilization of fly ash, improving the utilization rate of resources, and promoting sustainable development, thus providing a reference for the design and construction of saline soil roadbed engineering in seasonal frozen areas and the development and construction of saline land belts in seasonal and winter areas.

scholarly journals Effect of Freeze-Thaw Cycle on Shear Strength of Lime-Solidified Dispersion Soils

2020 ◽  
Vol 6 (1) ◽  
pp. 114-129 ◽  
Author(s):  
Meng Yao ◽  
Qing Wang ◽  
Bing Ma ◽  
Yaowu Liu ◽  
Qingbo Yu ◽  
...  
Keyword(s):  
Shear Strength ◽  
Mechanical Strength ◽  
Saline Soil ◽  
Mechanical Analysis ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Freeze Thaw ◽  
Sem Image ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

The freeze-thaw cycle of saline soil in the seasonal frozen area will produce diseases such as frost heave and thaw settlement, road frost boiling, collapse and uneven settlement. In order to reduce the occurrence of these undesirable phenomena, it is often necessary to improve the saline soil in engineering. In this paper, the typical carbonate saline soil in the west of Jilin Province, China is taken as the research object. By adding different content of lime (0%, 3%, 6%, 9%, 12%, 15%), the change of mechanical strength of lime solidified saline soil under different freeze-thaw cycles (0, 1, 3, 6, 10, 30, 60 times) is studied. The mechanical analysis is carried out by combining particle size analysis test and SEM image. The test results show that although repeated freeze-thaw cycles make the soil structure loose and the mechanical strength greatly reduced, the soil particles agglomerate obviously after adding lime, its dispersion is restrained by the flocculation of clay colloid, and the shear strength of soil is improved by the increase of the cohesive force between clay particles, and the optimal lime mixing ratio of the saline soil in this area is 9%.

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